Underwater multiple well installation

ABSTRACT

Clustered underwater wells are used as anchor piles for a production platform floating at the water surface. A drilling template transmits tension loads from the well-anchor piles to a tension member which connects to the floating platform and also serves to index drilling, completion and reworking operations on the wells in the cluster.

United States Patent [72] Inventors Folker H. Wels 3,366,173 1/1968 Mclntosh 166/.5 LasAitos; 3,504,740 4/1970 Manning 166/.5 John W. Hopkins, Saratoga, both of, Call!- 2,503,516 4/1950 Shrewsbury.... 175/8 [21] Appl. No. 797,850 3,063,507 11/1962 O'Neill et al.... 175/8 [22] Filed Feb. 10,1969 3,202,216 8/1965 Watts et a1 166/5 [45] Patented Aug. 24,1971 3,353,364 11/1967 Blanding et a1. 175/6 [73] Assignee Lockheed Aircraftcorporatiou 3,391,734 9/1968 Townsend, Jr. 166/.5 Burbank, Cam. 3,202,217 8/1965 Watts et a1 166/.5

Primary Examiner.lames A. Leppink {54] UNDERWATER MULTIPLE WELL INSTALLATION Attorneys-H. Donald V( and George C. Sullivan 4 Claims, 6 Drawing Figs.

[52] 11.8. C1 166/.5, 175/7 [51] Int. Cl E21b 33/035, 33/035, E21b /02 Field of Search 166/.5/.6; ABSTRACT; Clustered underwater wells are used as anchor 175/5109/8 6 piles for a production platform floating at the water surface. A drilling template transmits tension loads from the well-anchor [56] References cued piles to a tension member which connects to the floating plat- UNITED STATES PATENTS form and also serves to index drilling, completion and rework- 3 247,672 4/1966 Johnson 61/46 ing operations on the wells in the cluster.

.1". l 1 l I! 2%,; I all a L I 5 li E l l s i 22 \JIB 3 t l if w I 19 1 5 B u i a j I v 3 t; :5 N" l; ,5 '2 2|' 22 C 21 u i 23 5 e t 1H INVENTORS. FOLKER H.WEISS JOHN w. HOPKINS BY 4.

gent Attorney PATENTEDAUBZMSTI 3,601,189

SHEET 3 OF 3 1 NVENTORS. FOLKER H.WE|SS JOHN W. HOPKINS b "Agem $4 BMW Attorney UNDERWATER MULTIPLE WELL INSTALLATION This invention relates to methods-and apparatus for making an underwater multiple well installation.

The installation and maintenance of oil wellson the ocean floor become increasingly difficult with increasing water depth. If a diver is used to complete or rework a wellhead on he ocean floor, the depth of water in which the well can be placed is limited by the depth at which the diver can operate. If the wellhead is completed on the ocean floor by remote control from the surface, mating and fitup of the wellhead parts becomes more difficult as the water depth (the distance from the water surface to the well) increases. And if the wellhead is completed on the surface, greater water depths increase the complexity andcost of the piping and related structure needed to support the wellhead.

It is therefore an important object of the present invention; to install and maintain oil wells on the ocean floor as an integral part of a production platform floating in water depths in excess of those considered accessible for hydrocarbon production with current methods.

In the present invention an atmospheric capsule is placed over the well clusters on the ocean floor. Personnel are then transported from the surface to the atmospheric capsule in a sealed transporter. Such personnel can complete the well in the air chamber within the capsule at great depths under the water surface.

Those skilled in the art can appreciate that in the course of hydrocarbon production a number of procedures are required in the vicinity of the wells and prior to delivery of the products to a pipeline or storage facility. In offshore fields the equipment for these procedures such as separators, pumps, compressors, treating and holding facilities and the like, are located on platforms. In shallow water these platforms are rigid structures, supported on the sea floor. In deep water it becomes more desirable to utilize a floating platform anchored to the seafloor by generally vertical tension members.

It is a specific object of the present invention to anchor the platform by connecting the platform to the well casing of a number of wells so that the wells themselves serve as anchors without the need for auxiliary pilings or monuments in the ocean floor.

It is another object of the present invention to construct and operate a multiple well installation in a way that permits convenient and efficient operation of a large number of wells from a single platform.

In the present invention a center pipe guide and tension member and a drilling template are used in a novel way, both in the process of installing the wells and in the completed multiple well installation, to locate a group of oil wells in a precisely located and closely spaced cluster so that the output of all of the wells can be readily brought up to a single platform for production. The technique of using the center pipe guide and tension member and drilling template during installation of the wells and the manner in which these parts are incorporated in the completed structure constitute further, specific objects of the present invention.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what are now considered to be the best modes contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIGS. 1 through 4 are pictorial views illustrating different I steps in the installing and operation of one embodiment of th multiple well installation of the present invention;

FIG. 5 is a front elevation view in section through an atmospheric wellhead chamber; and

FIG. 6 is a bottom plan view taken along the line and in the direction indicated by the arrows 6-6 in FIG. 5.

In the underwater clustered well installation of the present invention the wellheads and the platform function as an integrated system. i

The first step in establishing the installation is to drill a bore in the desired area. A caisson of sufficient diameter and length for adequate support of a guide pipe 13 is then set in the bore and cemented in place in the conventional manner.

In FIG. 1 this bore and caisson is indicated by the reference numeral 11 and 10 respectively.

A drilling template 12 is an integral part of the caisson l0 and guide string 13 and is locked in place on the sea floor by cementing of the caisson 10 (see FIGS. 1, 2, 3. and '5).

In FIG. 1 the drilling rig 14 is shown mounted on a platform 16 of conventional semisubmersible design.

As best shown in FIGS. 5 and 6 the template 12 includes a number of disks l9 and pipes 21. The pipes 21 are, as best shown in FIG. 6, arranged in a circle about the center pipe 13. The pipes 21 are all on the same radius and are equally spaced circumferentially. The template thus locates the upper ends of the wells in a closely spaced cluster. The wells themselves may be slant drilled so as to extend out laterally for considerably distances from the upper end cluster. The inside diameter of each pipe 21 is large enough to receive and support the conductor pipes 22 and casings 23 of the wells which are drilled through these pipes 21.

The center pipe 13, performs several functions in the process of installing the multiple well installations of the present invention, and this pipe 13 also forms an important and permanent part of the structure of the completed installation.

The template 12 also performs several functions, both in the process of installing the wells and as a functional part of the structure of the completed installation. I

Drilling of the individual wells through the pipes 21 is accomplished (as illustrated in FIG. 2) by indexing a drilling unit 27 to the pipes 21 and performing subsequent operations sequentially around the center pipe 13 as a guide.

During the drilling phase and after the placement and cementing of the caisson 10 and template 12, the pipe guide and tension member 13 is tensioned not only to prevent its collapse but more so to aid in anchoring and positioning of the floating drilling vessel over the location.

After all the wells are drilled'and capped, an atmospheric capsule 28 is lowered on the guide pipe 13. The capsule 28 is emplaced around and sealed to he guide pipe and tension member 13 and template 12. All water is evacuated from the interior of the capsule 28 at a later time by equipment carried in a personnel transporter 31, so that the capsule provides an air chamber over the individual wells. Fresh air can be conducted to the chamber through the center pipe 13.

As best shown in FIG. 5 the capsule 28 includes a number of access hatches 29 which are aligned with the individual wells to facilitate vertical access for reworking of the wells.

A watertight personnel transporter 31 engages with the hatch trunks in sealing engagement and permits personnel to be transported from the surface to the interior of the capsule 28. As shown in FIG. 3 the center'pipe 13 is used as a guide for vertical movement of this transporter 31. 7

Personnel enters the interior of the capsule 28 to complete the wells by installing the Christmas trees 32, flowlines 33 and other necessary equipment.

As shown in FIG. 5 the flow lines 33 are conducted upward to the surface through the interior of the pipe 13.

The production from the individual wells can also be manifolded into a single conduit.

The manner in which the center pipe 13 functions to anchor the production platform (FIG. 4) is an important feature of the present invention and will now be described.

As best shown in FIG. 5, the template 12 forms a connection between the pipe 13 and the pipes 22 and 23 of the individual wells in a manner such that any upward tension on the pipe 13 is resisted by the weight of the pipes 22 and 23 and by the shear bond between the well casings and the soil. The center pipe 13 is thus firmly held in position against any upward movement. When the center pipe 13 is then connected to the production platform 17, either by direct connection to the platform deck or by connection to the flotation bottles 17, as illustrated in FIG. 4, the pipe 13 formb a very effective tether for the platform.

A plurality integrated clusters of wells are connected to a single platfonn. FIG. 4 shows four integrated clusters connected to the production platform 18.

While I have illustrated and described the preferred embodiments of my invention it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

We claim:

1. An underwater floor well installation below the water surface comprising,

a plurality of well pipes having upper ends clustered together in closely spaced relation adjacent the unde'rwater floor and extending downwardly into the underwater floor,

a horizontal, substantially flat template mounted on the underwater floor and connected to and encompassing said upper ends of said well pipes,

a capsule having a large bottom opening adapted to be lowered over the upper ends of said well pipes and making a water tight connection with said template surroundsaid capsule including a plurality of upper access hatches aligned with the plurality of wells to provide vertical access to said wells,

a floating platform at the water surface, and

tether means connecting said template and said floating platform.

2. The invention defined in claim 1 including a watertight personnel transporter engageable in sealing engagement with at least one of said access hatches for transporting personnel and equipment from the water surface to said capsule.

I 3. The invention defined in claim 2 wherein saidtether is a single tubular tension member anchoring said floating platform to the underwater floor at said template,

said tether means providing the sole anchor for said floating platform.

4. The invention defined in claim 3 including flow lines,

said flow lines being individually connected to said upper ends of said well pipes in said capsule and connecting to said floating platform through said tubular tension member. 

1. An underwater floor well installation below the water surface comprising, a plurality of well pipes having upper ends clustered together in closely spaced relation adjacent the underwater floor and extending downwardly into the underwater floor, a horizontal, substantially flat template mounted on the underwater floor and connected to and encompassing said upper ends of said well pipes, a capsule having a large bottom opening adapted to be lowered over the upper ends of said well pipes and making a water tight connection with said template surrounding said plurality of well pipes, said capsule and said template defining an air chamber over and in communication with said upper ends of said plurality of well pipes, said capsule including a plurality of upper access hatches aligned with the plurality of wells to provide vertical access to said wells, a floating platform at the water surface, and tether means connecting said template and said floating platform.
 2. The invention defined in claim 1 including a watertight personnel transporter engageable in sealing engagement with at least one of said access hatches for transporting personnel and equipment from the water surface to said capsule.
 3. The invention defined in claim 2 wherein said tether is a single tubular tension member anchoring said floating platform to the underwater floor at said template, said tether means providing the sole anchor for said floating platform.
 4. The invention defined in claim 3 including flow lines, said flow lines being individually connected to said upper ends of said well pipes in said capsulE and connecting to said floating platform through said tubular tension member. 